In sensor systems which measure a particular physical state and then transmit it to a receiver for further processing, different supply voltages may be required for the transmitter or for the sensor. Thus, for example, a transmitter stage in a pressure monitoring system for vehicle tires requires a supply voltage of 2.1 volts. For the associated pressure sensor, however, a supply voltage of 2.5 volts is needed. If the transmitter is fed with a supply voltage of 2.5 volts, this leads to an increased power consumption in the transmitter. It is, therefore, appropriate to select a supply voltage of 2.1 volts for the transmitter and to increase this voltage by an additional circuit in order to ensure that the transmitter will be operable.
Possible constructions for such circuits are low-frequency step-up switch mode power supplies or charge-pumping systems. Such circuits increase the supply voltage to the voltage needed for the sensor, in most cases by charging up a capacitor. The disadvantage of such a circuit is an increased space requirement and higher costs, which stand in the way of the requirement for high integration density and more advantageous mass production.